The majority of snaps expose their functionality via applications that run on the local system. Most of these applications are started either from the command line, the graphical desktop, or as services that run automatically.
A single snap may provide multiple applications and services. With a database snap, for example, you might expect an interactive client application alongside the service daemon.
Snaps manage their own services without the need for manual intervention. However, experienced administrators may want to interact with a snap’s services to help improve their integration with the local environment. For that reason, snapd offers a set of commands to allow a snap’s services to be inspected and their statuses changed.
Listing services
Use snap services to lists all the services added to the system by the currently installed and enabled snaps:
$ snap services
Service Startup Current Notes
bluez.bluez enabled inactive -
bluez.obex enabled inactive -
cups.cups-browsed enabled active -
cups.cupsd enabled active -
docker.dockerd enabled active -
juju.fetch-oci disabled inactive -
lxd.activate enabled inactive -
lxd.daemon enabled inactive socket-activated
lxd.user-daemon enabled inactive socket-activated
multipass.multipassd enabled inactive -
nextcloud.apache disabled inactive -
nextcloud.logrotate disabled inactive -
nextcloud.mdns-publisher disabled inactive -
nextcloud.mysql disabled inactive -
nextcloud.nextcloud-cron disabled inactive -
nextcloud.nextcloud-fixer disabled inactive -
nextcloud.php-fpm disabled inactive -
nextcloud.redis-server disabled inactive -
nextcloud.renew-certs disabled inactive -
Adding a snap name as an argument will list only those services added by that snap:
$ snap services lxd
Service Startup Current Notes
lxd.activate enabled inactive -
lxd.daemon enabled inactive socket-activated
lxd.user-daemon enabled inactive socket-activated
The output includes the service name, whether the service is started when the system starts up, and whether it’s currently running.
Restarting services
Services are restarted using the snap restart <snap name> command. This may be necessary if you’ve made custom changes to the snap application, for example, which the service needs to reload.
By default, all services for a specified snap will be restarted:
$ sudo snap restart lxd
Restarted.
Using a more specific service name performs the same operation on an individual service:
$ sudo snap restart lxd.daemon
Restarted.
The option to perform an operation on all of a snap’s services, or on one specific service, is common to all commands that operate on services.
If a service supports reloading, enabling the service to remain running while loading a new configuration, this can be requested with the --reload option:
$ sudo snap restart --reload lxd.daemon
Restarted.
Starting and stopping services
The start and stop commands control whether a service should be currently running:
$ sudo snap stop lxd.daemon
Stopped.
$ sudo snap start lxd.daemon
Started.
As mentioned above, these commands can operate both on individual snap’s services and on all services for a named snap, depending on the parameter provided.
To prevent a service from starting on the next boot, use the --disable option:
$ sudo snap stop --disable lxd.daemon
The start command includes an --enable option to re-enable the automatic starting of a service when the system boots:
$ sudo snap start --enable lxd.daemon
Inspecting logs
If you need to see the log output for a snap’s services, use the logs
command. As with the services command, you can specify either a snap name to
see the logs for all the services it contains, or the name of a specific
service within a snap:
$ sudo snap logs lxd
2018-09-14T10:38:23Z lxd.daemon[11096]: => LXD is ready
(...)
$ sudo snap logs lxd.daemon
2022-07-15T17:13:04+01:00 lxd.daemon[1389234]: => LXD exited cleanly
2022-07-15T17:13:04+01:00 lxd.daemon[370462]: ==> Stopped LXD
2022-07-15T17:13:04+01:00 lxd.daemon[370462]: => Stopping LXCFS
2022-07-15T17:13:04+01:00 lxd.daemon[555302]: Running destructor lxcfs_exit
2022-07-15T17:13:05+01:00 lxd.daemon[370462]: ==> Stopped LXCFS
2022-07-15T17:13:05+01:00 lxd.daemon[370462]: => Cleaning up PID files
2022-07-15T17:13:05+01:00 lxd.daemon[370462]: => Cleaning up namespaces
2022-07-15T17:13:05+01:00 lxd.daemon[370462]: => All done
2022-07-15T17:13:05+01:00 systemd[1]: snap.lxd.daemon.service: Deactivated successfully.
2022-07-15T17:13:05+01:00 systemd[1]: Stopped Service for snap application lxd.daemon.
By default, only the last 10 lines are output. This can be changed with the -n= option which can accept either a number or all for the entire log:
snap logs -n=all lxd.daemon
Adding the -f option will keep log output open so you can follow new entries as they occur:
$ sudo snap logs lxd -f
The size and rate of log output can be limited by placing a snap within a quota group. See Journal log limits for more details.
Last updated 2 years ago.